Much to my chagrin, yet another tube experienced a sudden decompression while my bicycle was sitting idly in my apartment. It is not unprecedented, and was described in my opening comment. The common denominators are that the failure is occurring where the valve is bonded to the tube, and it occurs within hours after I've topped off the tire. I am not riding as frequently as I used to, so within several days the tires can get pretty low. I do not know whether the frequent inflating and deflating is causing the problem.

To address the possibility that the friction-based chuck installed on my pump was contributing to the problem, I purchased that company's locking-lever style chuck. Unfortunately, I haven't figured out how to get that adjusted well enough to stay on the valve.

I have replaced the plastic rim strips with cotton.

On this latest occasion, I couldn't help but notice that the workmanship where the valve is bonded to the tube is seriously flawed. I compared it to a new tube, and the difference is profound! I guess it's possible that's how that junction looks after a tube has been in use for a while, but I won't be sure until I've had an opportunity to replace another tube. In the future, I will be sure to inspect each new tube before installing it.